Study of applied electrical field effect on semiconductor crystall growth mechanism from melt and crystal growth for x-ray detectors

对液相电外延晶体生长进行了数值模拟和实验研究。采用控制体积法对连续性方程、Navier-Stokes方程、能量方程和考虑电迁移的传质方程进行描述，并采用SIMPLE技术进行求解。数值结果表明，即使系统温度保持不变，衬底温度也会因通电引起的Peltie效应而降低，温度分布会引起自然对流。为了抑制自然对流，施加磁场是有益的。然而，在强磁场下观察到空穴。因此，研究了旋转对液体对流的影响，旋转对液体对流的抑制作用与磁场相似。旋转引起的Coliori力抑制了液体中的对流，并且生长界面附近的浓度梯度必须陡峭，因为高密度材料将被离心力去除。结果表明，旋转可以提高晶体的生长速率。实验中，Si、GaAs衬底与液体发生反应，并得出需要CdTe衬底的结论。在CdTe衬底上成功生长出厚度为23 μm的CdTe晶体。研究了生长温度对晶体质量的影响。

Crystal growth by Liquid Phase Electroepitaxy was studied numerically and experimentally. Continuity, Navier-Stokes, Energy equations and Mass transfer equation considering electro-migration were descritized by control volume method and solved by SIMPLE technique. Numerical results show that substrate temperature is decreased by Peltie effect caused by electric application and natural convection is caused by the temperature distribution even if the system temperature was kept constant. In order to suppress the natural convection, magnetic field application is beneficial. However, holes are observed under strong magnetic fields. Therefore, effect of rotation, which has similar effect on suppression of convection to the magnetic field, on the liquid convection was investigated. Convection in the liquid was suppressed by Coliori force caused by rotation and concentration gradient near the growth interface must be steep because high density materials will be removed by centrifugal force. As the results, it can be expected that crystal growth rate becomes higher by applying rotation.In the experiments, it was shown that Si, GaAs substrates reacted with liquid and it was concluded that CdTe substrate is required. CdTe crystal with 23 μm thickness was successfully grown on the CdTe substrate. Effect of growth temperature on the crystal quality was also investigated.